Transferring orbital angular momentum to an electron beam reveals toroidal and chiral order

Auteurs

Nguyen K.X., Jiang Y., Cao M.C., Purohit P., Yadav A.K., García-Fernández P., Tate M.W., Chang C.S., Aguado-Puente P., Íñiguez J., Gomez-Ortiz F., Gruner S.M., Junquera J., Martin L.W., Ramesh R., Muller D.A.

Référence

Physical Review B, vol. 107, n° 20, art. no. 205419, 2023

Description

Orbital angular momentum (OAM) and torque transfer play central roles in a wide range of magnetic textures and devices including skyrmions and spin-torque electronics. Analogous topological structures are now also being explored in ferroelectrics, including polarization vortex arrays in ferroelectric/dielectric superlattices. Unlike magnetic toroidal order, electric toroidal order does not couple directly to linear external fields. Instead, we find that the presence of an electric toroidal moment in a ferrorotational phase transfers measurable torque and OAM to a localized electron beam in the ballistic limit. We record these torque transfers from a high-energy electron beam using a momentum-resolved detector. This approach provides a high-sensitivity method to detect polarization fields and their more complex order parameters and topologies. In addition to toroidal order, we also demonstrate high-precision measurements of vorticity and chirality for polar vortexlike phases.

Lien

doi:10.1103/PhysRevB.107.205419